It has previously been proposed to monitor the temperature of a turbine engine, particularly at over-temperature levels, and one such over-temperature monitoring system is disclosed in U.S. Pat. No. 3,931,619. Another system of this general type is disclosed in the copending patent application of Geoffrey Hancock, U.S. patent application Ser. No. 197,008, filed Oct. 14, 1980, now U.S. Pat. No. 4,315,296, and assigned to the assignee of the present invention. In these prior arrangements, predetermined weighting characteristics were established and alarm signals were energized when the turbine engine exceeded such predetermined overall limits. These control systems characteristically involve a summation function in which the time at some very high temperature would be equated to a longer time at a slightly lower temperature, and the sum of the weighted factors would be employeed to provide an output indication which would give a rough indication of the over-temperature stress or damage to the turbine engine which may have occurred.
However, it would be desirable to have a more accurate indication of the precise amount of time that the turbine engine has been operated, and that it has been operated at particular temperature levels. In addition, supplemental information such as the number of times that the engine has started is also relevant in determining whether periodic maintenance of the engine is appropriate. Further, in the analysis of the maintenance status of a turbine engine or the reason for certain anomalies in engine performance, it is frequently desirable to be able to determine the details of the recent past history of the operation of the engine in greater detail than has been possible heretofore.
Accordingly, the present invention is intended to overcome the shortcomings of the prior art systems and to provide the more complete historical information of the type outlined hereinabove.